Tire dimensions are important, particularly tire diameters. For example, tires should be matched, in terms of diameter when mounting them in dual wheel applications, such as on heavy duty trucks, where matched tire sizing is required for load carrying purposes, etc. In addition, in retreading operations it is important to determine the exact tire dimensions, particularly in minimum and maximum diameters of buffed tire casings in order to select the proper matrix for retreading purposes. One way to measure the buffed diameter of a tire casing is to pull a band tightly around the center of the casing and then reading the physical dimension of the tire, generally in vernier scale calibration, in terms of either circumference or, if so calibrated, directly in diameter. It is better practice to measure the circumference of the tire and then calculate the diameter therefrom since a direct diameter measurement of the tire is more complicated due to tire contour and is often not fully accurate due to out-of-round conditions of the tire casing. Once the correct physical dimension is determined, the operator then must consult a separate maintenance chart in order to select the proper matrix. This is not only time consuming, but also can lead to errors in selecting the proper chart to determine the proper matrix.
U.S. Pat. No. 1,797,389 to Woock discloses a measuring tape which is specifically designed and adapted for measuring the exterior cross-sectional peiphery or cross-sectional profile of an automobile tire. However, the tape is not calibrated in matrix code, is not oriented to be circumferentially placed around the tire and does not appear to be specifically used for determining matrix sizes. German Pat. No. 917,272 to Zangl appears to disclose a tire measuring tape somewhat similar to that shown by Woock. There appears to be no indication in regard to tape calibrations.
U.S. Pat. No. 2,434,156 to Heintz discloses a method and device for retreading tires wherein a tape (not shown) is placed along line 3 such that the buffed contour of the tire from bead-to-bead is measured. The dimensions of the tire are then compared to a table, as shown in FIGS. 5 and 8, whereupon the appropriate size matrix is chosen for retreading the tire.
U.S. Pat. No. 3,007,251 to Rawls discloses a method and apparatus for measuring tire casings, both of which differ from that of the present invention inasmuch as they are used to measure cross-sectional contour and the cross-sectional dimension. In addition, the matrix appears to be based on the measured bead-to-bead dimension.
U.S. Pat. No. 3,633,279 to Frezlev et al discloses an apparatus for measuring tire parameters of the tire carcass, which apparatus however does not disclose the use of circumferentially displaced tape or a calibrated scale which indicates matrix dimensions.
U.S. Pat. No. 3,986,267 to Taylor discloses a tire measuring instrument for the diameter and bead-to-bead dimension of a tire casing and correlating such measurement to a particular retreading matrix. The mechanism in question appears to measure the cross-sectional periphery of the tire as well as its diameter, but not the circumferential periphery. In addition, Taylor does not disclose a calibrated tape which is used to indicate matrix dimensions.
U.S. Pat. No. 1,962,716 to Johnson discloses a spring wire gauge for measuring the treads of flanged wheels that are primarily used on railway stock. Johnson however neither describes the form of calibrations on his measuring plate nor illustrates a measuring device oriented specifically to tires.
U.S. Pat. No. 3,685,155 to Oblander discloses a sewing measurement device comprising a coded tape which is used to fit different parts of a person's body in order to determine body dimensions for sewing parameters. Each area of the strip has different indicia relating to particular body dimensions and these areas may be color coded to indicate particular deviations.